The present invention relates generally to heating, ventilating and air conditioning systems and, more particularly, to single-package, wall-mount air conditioners for use in cooling buildings or rooms within buildings in need of cooling and/or ventilation.
Single-package, wall-mount air conditioners are mounted to an exterior side of an exterior wall of a building or a room within a building and incorporate both evaporator and condenser coil assemblies within a single cabinet. These wall-mount air conditioners are typically used to deliver conditioned or ventilation air to enclosed structures such as classrooms, telecommunication shelters, electronic equipment rooms, and any other buildings or rooms within buildings in need of cooling and/or ventilation.
In a typical construction, these wall-mount air conditioners include an internal evaporator compartment that is positioned at an upper portion of the cabinet and houses the evaporator coil assembly, a blower box that is positioned below the evaporator coil assembly and houses one or more blowers, and a condenser compartment positioned that is positioned below the blower box and houses the condenser coil assembly. Conditioned supply air is delivered from the evaporator compartment through a supply air opening in the exterior wall of the building and into the building. Return air is delivered from within the building to the blower box through a return air opening in the exterior wall 12 and is then recirculated by the blowers to the building through the evaporator compartment as conditioned supply air. A large fan in the condenser compartment draws in outside air and blows it across the condenser coil assembly to cause cooling of the heat exchange medium within the condenser coils.
Some types of these wall-mount air conditioners include an economizer unit that allows the air conditioner to be operated without mechanical cooling by drawing in fresh outside air when that air is sufficiently cool to handle the heating load within the building. When the air conditioner is operating in this economizer cooling mode, a damper assembly is placed in a position to allow fresh outside air to be drawn by the blowers into the blower box and then delivered into the building through the evaporator compartment. Some or all of the return air from the building is then redirected to the condenser compartment and exhausted outwardly from the cabinet during the economizer cooling mode of operation.
The economizer unit is positioned generally in-line with the return air opening in the exterior wall between the blower box and the condenser compartment. The fresh outside air intake for the economizer unit may thus be positioned in close proximity to the exhaust for the condenser compartment. As a result, some of the return air that is exhausted from the condenser compartment may enter the economizer unit through the fresh outside air intake. The mixing of the warmer return air with the fresh outside air is disadvantageous because it may increase the temperature of the air mixture enough to exceed the set point temperature that causes the air conditioner to switch from the economizer cooling mode to the mechanical cooling mode. A need has thus arisen for improvements to these wall-mount air conditioners that will reduce the mixing of return air with fresh outside air so that they may operate in the economizer cooling mode for extended periods of time and thereby benefit from the reduced operational costs that result from operating in the economizer cooling mode.